Simple problem, what am I missing?

[LostManAbroad]

Okay so I am trying to do something that I thought would be relatively simple but the simplest part of it is simply eluding me and I cannot figure it out. All that I am trying to do is expand an empty yard on this map in order to put down buildings for a new farm. Below is a picture of the yard I am expanding.



The problem comes when I try and remove the foliage from the area behind the yard. What am I doing wrong? I thought I could just click on the button for Terrain Foliage Paint Mode and then use the RMB to remove what is already there. It won't delete though. I am not sure if I have to first select the type of foliage that is there before I can remove it. If so, that may be a slight issue as I am not exactly sure what it is. It isn't just normal grass. I think it is wildflowers but I'm not sure. Below is a closer view so people can see the foliage itself.



Can anyone advise me what I need to do to get rid of the foliage in the area I want to expand my yard into?

[hpmc13]

I'm pretty sure that you do have to pick the type of foliage in order to remove it. I'm also pretty sure the you are subtracting it; make sure that is what is set to your RMB. I just started making maps so I'm learning, too. I could be wrong on this.

[chrisbitz]

Check the options on your RMB too - there is remove and subtract for instance, and they have similar meanings, but work in different ways.
alternatively, you could try replace - with 0 in the bitmask?